9 research outputs found
Determination of Electromagnetic Source Direction as an Eigenvalue Problem
Low-frequency solar and interplanetary radio bursts are generated at
frequencies below the ionospheric plasma cutoff and must therefore be measured
in space, with deployable antenna systems. The problem of measuring both the
general direction and polarization of an electromagnetic source is commonly
solved by iterative fitting methods such as linear regression that deal
simultaneously with both directional and polarization parameters. We have
developed a scheme that separates the problem of deriving the source direction
from that of determining the polarization, avoiding iteration in a
multi-dimensional manifold. The crux of the method is to first determine the
source direction independently of concerns as to its polarization. Once the
source direction is known, its direct characterization in terms of Stokes
vectors in a single iteration if desired, is relatively simple. This study
applies the source-direction determination to radio signatures of flares
received by STEREO. We studied two previously analyzed radio type III bursts
and found that the results of the eigenvalue decomposition technique are
consistent with those obtained previously by Reiner et al. (Solar Phys. 259,
255, 2009). For the type III burst observed on 7 December 2007, the difference
in travel times from the derived source location to STEREO A and B is the same
as the difference in the onset times of the burst profiles measured by the two
spacecraft. This is consistent with emission originating from a single,
relatively compact source. For the second event of 29 January 2008, the
relative timing does not agree, suggesting emission from two sources separated
by 0.1 AU, or perhaps from an elongated region encompassing the apparent source
locations.Comment: 22 pages, 7 figures, Accepted in Solar Physic
Effect of lead acetate on Sertoli cell lactate production and protein synthesis in vitro
The effects of lead acetate on protein synthesis and lactate production by cultures of rat Sertoli cells in vitro were studied. Sertoli cell cultures prepared from 20 day old Sprague-Dawley rats were exposed to 0.01, 0.05 and 0.10 mM lead acetate. Lactate production was significantly elevated by all concentrations of lead after 3, 6, 9 and 12 hours of exposure. Protein biosynthesis as measured by [ 3 H]-leucine incorporation was significantly depressed by 0.05 and 0.10 mM lead acetate after 2 hours of exposure. These results support the hypothesis that lead acetate may inhibit spermatogenesis by a disturbance of the metabolic activities of the Sertoli cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42549/1/10565_2004_Article_BF00122696.pd
Frequency tuning of single photons from a whispering-gallery mode resonator to MHz-wide transitions
Ruolo della RM a doppio contrasto rispetto alla TC multidetettore nella diagnosi del piccolo epatocarcinoma (â€3 cm) su cirrosi
The use of understory species as indicators of landform ecosystem type in heavily disturbed forest: an evaluation in the Haut-Saint-Laurent, Quebec
Performance of the ALEPH detector at LEP
The performance of the ALEPH detector at the LEP e+eâ collider is reviewed. The accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified. Calorimeters are used to measure photons and neutral hadrons, and the accuracy obtained in energy and angle is given. An essential property of the detector is its ability to identify particles; the performance in identification of electrons, muons, neutrinos (from missing energy), charged hadrons, Ï0's and V0's is described